removeDuplicates.js

function removeDuplicates(str) {
  //remove all non alphabets 
  var expression = /[^a-zA-Z]/g;
  var unique = [];
  var repeated = [];
  var obj = {
    uniques: [unique],
    duplicates: [],
  };
  
  str = str.replace(expression, "").split();
  
  //search for repeating letters
  for (var i = 0; i < str.length; i++) {
    for (var j = 0; j < str[i].length; j++) {
      if (unique.indexOf(str[i][j]) === -1) {
        unique.push(str[i][j]);
      } else {
        repeated.push(str[i][j]);
      }
    }
  }

  
  return obj;
}
removeDuplicates("xxyxzlp346");